outcome/test/tests/experimental-p0709a.cpp

/* Unit testing for outcomes
(C) 2017-2019 Niall Douglas <http://www.nedproductions.biz/> (7 commits)


Boost Software License - Version 1.0 - August 17th, 2003

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*/

#include <boost/outcome/experimental/status_result.hpp>

#include <climits>  // for INT_MAX
#include <cstdio>

// status_code<erased<intptr_t>>
using error = BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::error;
// Outcome's result must be told when it is dealing with an erased status code
template <class T, class E> using result = BOOST_OUTCOME_V2_NAMESPACE::experimental::status_result<T, E, BOOST_OUTCOME_V2_NAMESPACE::policy::all_narrow>;

enum class arithmetic_errc
{
  success,
  divide_by_zero,
  integer_divide_overflows,
  not_integer_division
};

class _arithmetic_errc_domain;
using arithmetic_errc_error = BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::status_code<_arithmetic_errc_domain>;

class _arithmetic_errc_domain : public BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::status_code_domain
{
  using _base = BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::status_code_domain;

public:
  using value_type = arithmetic_errc;

  constexpr explicit _arithmetic_errc_domain(typename _base::unique_id_type id = 0x290f170194f0c6c7) noexcept : _base(id) {}
  static inline constexpr const _arithmetic_errc_domain &get();

  virtual _base::string_ref name() const noexcept override final  // NOLINT
  {
    static string_ref v("arithmetic error domain");
    return v;  // NOLINT
  }

protected:
  virtual bool _do_failure(const BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::status_code<void> &code) const noexcept override final  // NOLINT
  {
    assert(code.domain() == *this);                                     // NOLINT
    const auto &c1 = static_cast<const arithmetic_errc_error &>(code);  // NOLINT
    return c1.value() != arithmetic_errc::success;
  }
  virtual bool _do_equivalent(const BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::status_code<void> &, const BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::status_code<void> &) const noexcept override final { return false; }  // NOLINT
  virtual BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::generic_code _generic_code(const BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::status_code<void> &) const noexcept override final { return {}; }                         // NOLINT
  virtual _base::string_ref _do_message(const BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::status_code<void> &code) const noexcept override final                                                          // NOLINT
  {
    assert(code.domain() == *this);                                     // NOLINT
    const auto &c1 = static_cast<const arithmetic_errc_error &>(code);  // NOLINT
    switch(c1.value())
    {
    case arithmetic_errc::success:
      return _base::string_ref("success");
    case arithmetic_errc::divide_by_zero:
      return _base::string_ref("divide by zero");
    case arithmetic_errc::integer_divide_overflows:
      return _base::string_ref("integer divide overflows");
    case arithmetic_errc::not_integer_division:
      return _base::string_ref("not integer division");
    }
    return _base::string_ref("unknown");
  }
  BOOST_OUTCOME_SYSTEM_ERROR2_NORETURN virtual void _do_throw_exception(const BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::status_code<void> &) const override final { abort(); }  // NOLINT
};

constexpr _arithmetic_errc_domain arithmetic_errc_domain;
inline constexpr const _arithmetic_errc_domain &_arithmetic_errc_domain::get()
{
  return arithmetic_errc_domain;
}


// Tell status code about the available implicit conversion
inline arithmetic_errc_error make_status_code(arithmetic_errc e)
{
  return arithmetic_errc_error(BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::in_place, e);
}

BOOST_OUTCOME_V2_NAMESPACE_BEGIN
namespace trait
{
  // Tell Outcome that arithmetic_errc is convertible into std::error
  template <> struct is_error_type_enum<error, arithmetic_errc>
  {
    static constexpr bool value = true;
  };
}
BOOST_OUTCOME_V2_NAMESPACE_END
// And tell Outcome how to perform the implicit conversion
inline error make_error_code(arithmetic_errc e)
{
  return arithmetic_errc_error(BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::in_place, e);
}


result<int, error> safe_divide(int i, int j)
{
  if(j == 0)
  {
    return arithmetic_errc::divide_by_zero;
  }
  if(i == INT_MIN && j == -1)
  {
    return arithmetic_errc::integer_divide_overflows;
  }
  if(i % j != 0)
  {
    return arithmetic_errc::not_integer_division;
  }
  return i / j;
}

int caller2(int i, int j)
{
  auto r = safe_divide(i, j);
  if(r)
  {
    return r.value();
  }
  if(r.error() == arithmetic_errc::divide_by_zero)
  {
    return 0;
  }
  if(r.error() == arithmetic_errc::not_integer_division)
  {
    return i / j;  // ignore
  }
  if(r.error() == arithmetic_errc::integer_divide_overflows)
  {
    return INT_MIN;
  }
  return 0;
}

int main()
{
  printf("%d\n", caller2(5, 6));  // NOLINT
  return 0;
}